Plural visual indicator assembly energizable through two input terminals



Sept. 22, 1970 P. J. VAN BENSCHOTEN 3,530,501

PLURAL VISUAL INDICATOR ASSEMBLY ENERGIZABLE THROUGH TWO INPUT TERMINALSFiled Dec. 11, 1968 INVENTOR P k %m Zane/ om BY 67 @M dd! ATTORNEYSUnited States Patent PLURAL VISUAL INDICATOR ASSEMBLY ENER- GIZABLETHROUGH TWO INPUT TERMINALS Peter J. Van Benschoten, Rancho Santa Fe,Calif., as-

signor to Oak Electro/Netics Corp., a corporation of Delaware Filed Dec.11, 1968, Ser. No. 782,972 Int. Cl. HOlj 1/60 US. Cl. 315-129 6 ClaimsABSTRACT OF THE DISCLOSURE This invention relates to a circuit andassembly for energizing a plurality of loads, and more particularly to acircuit for selectively energizing one or a combination of loads througha single pair of input terminals.

A pair of visual indicator lamps are typically energized, eitherindividually or simultaneously, through three input terminals, in whichone terminal is connected in common to both lamps. By connecting anelectrical source across an individual terminal and the common terminal,either one of the lamps can be energized. By connecting the electricalsource across both individual terminals, both lamps are energized.

While such a three input terminal circuit is satisfactory in manyapplications, it is sometimes desirable to be able to individually orsimultaneously energize the pair of lamps through a single pair of inputterminals. For example, the present invention allows a two lamp assemblyto be substituted for a one lamp assembly, without requiring replacementof the two terminal lamp socket receptacle.

In addition, a three terminal lamp assembly is considerably moreexpensive to tool and manufacture than a two terminal lamp assembly. Thecost is further increased when the lamp assembly is to be incorporatedwith other structure, such as in an illuminated pushbutton switch. Eachelectrical terminal requires sliding contacts or other structure and anadditional terminal significantly increases the cost of the assembly.

One object of the invention is the provision of a circuit for energizingeither individually or in combination a plurality of loads through asingle pair of input terminals.

One feature of the invention is the provision of a two lamp indicatorassembly in which either or both lamps may be energized through a singlepair of input terminals.

Another feature is the provision of a two lamp energizing circuit inwhich diodes are associated with each lamp in order to pass DC currentsof different polarity to each lamp. When AC voltage is connected to thecircuit, both lamps are energized.

Further features and advantages will be apparent from the followingdescription and from the drawings, in which:

FIG. 1 illustrates a two lamp assembly incorporated in an illuminatedpushbutton switch;

FIG. 2 is a schematic diagram of the lamp circuit of FIG. 1;

FIG. 3 is a schematic diagram of the lamp circuit connected to a powersupply for energizing the lamps; and

FIG. 4 is a diagram of the voltage Waveform available from the powersupply of FIG. 3.

While an illustrative embodiment of the invention is ice \ shown in thedrawings and will be described in detail herein, the invention issusceptible of embodiment in many diiferent forms and it should beunderstood that the present disclosure is to be considered as anexemplification of the principles of the invention and is not intendedto limit the invention to the embodiment illustrated. The scope of theinvention Will be pointed out in the appended claims.

Turning to FIG. 1, a plurality of energizable loads are illustrated, inthe form of a pair of visual indicator lamps 10 and 11. The lamps arecontained within a single socket assembly 13 which is slidably mountedwithin a receptacle assembly, not illustrated. These assemblies form anilluminated pushbutton switch, in which an operator manually depressessocket assembly 13 in order to engage the receptacle and energize thelamps 10 and/or 11.

Lamps 10 and 11 are mounted Within a cylindrical insulated housing 16having a base 17, of insulating material, at one end, with a pair ofelectrical input terminals 19 and 20 secured thereto. The opposite endof cylindrical housing 16 is covered with a transparent lens 22 whichallows light from lamps 10 and 11 to be transmitted therethrough whenthe lamps are energized. An opaque wall 24 within housing 16 separatesthe lamps, forming light tight enclosures or chambers 25 and 26therefor. The lamps are mounted on a wall 27 of insulating material,which forms the bottom portion of the chambers.

Electrical input terminals 19 and 20 may take any desired form, and areillustrated for an illuminated pushbutton switch assembly. Terminal 19consists of a button extending from insulators 28, which are mounted atthe end of a cylindrical metal housing 29 which forms contact 20. Asassembly 13 is pressed downwardly, it engages a conventional plunger andcontact pin of the switch receptacle, thereby connecting contacts 19 and20 to the circuit of FIG. 3.

In FIG. 2, the lamp circuit contained within socket 13 is illustrated indetail. Either lamp 10 or 11, or both lamps, may be energized byelectrical power from terminals 19 and 20. For this purpose, oneterminal line of each of the lamps 10 and 11 is connected to a commonline 40 which directly connects to terminal 20. The opposite terminalline of lamp 10 is connected through a unidirectional conduction device,in the form of a diode 42, to a common line 43 which directly connectswith terminal 19. Similarly, the opposite terminal line of lamp 11 isconnected through another unidirectional conduction device, in the formof a diode 45, to line 43. Diodes 42 and 45 are oppositely poled, sothat only diode 42 is conductive when terminal 19 is positive relativeto terminal 20, and conversely only diode 45 is conductive when terminal19 is negative relative to terminal 20.

In operation, terminals 19 and 20 are connected to an electrical sourcewhich can supply energy of different characteristic, herein positivepolarity DC voltage, to either terminals 19 or 20, or an AC voltagethereacross. When terminal 19' is coupled to a positive DC voltagerelative to terminal 20, a current path is formed through line 43 anddiode 42, lamp 10, and line 40 to terminal 20. This causes only lamp 10to be energized. Lamp 11 cannot be energized because diode 45 isback-biased and blocks current flow through the lamp. When the polarityof the DC voltage is reversed, a current path is formed from terminal 20and through lamp 11, diode 45, and line 43 to terminal 19. In this case,only lamp 11 is energized.

When both lamps 10 and 11 are to be energized, an AC voltage isconnected to terminals 19 and 20. When the AC voltage goes positive atterminal 19*, lamp 10 is energized, and when the AC voltage goespositive on the opposite half cycle at terminal 20, lamp 11 isenergized. The AC voltage is chosen to have a frequency in excess of theperception time of the human eye. Thus, although each lamp isalternately energized, the visual perception to the human eye is that ofa continuous energized lamp.

Diodes 42 and 45 are mounted within housing 29, as seen in FIG. 1. Asillustrated, the cylindrical housing 29 extends downward from base 17.Diodes 42 and 45 are placed within the opening defined by housing 29 andinsulator 28, after which an epoxy resin may be poured therein in orderto hold the diodes in place.

A power supply suitable for energizing the circuit of FIG. 2 isillustrated in FIG. 3. A transformer 52 has an input winding 53 with apair of terminals 54, 55 connectable to a conventional source of 60cycle AC line current. An output winding 56 of transformer 52 has aturns ratio, relative to input winding 53, chosen to step down thevoltage to a magnitude suitable for lamps and 11. One side of winding 56is directly connected to the receptacle structure which engages terminal20. The other side of winding 56 is connected to a unidirectionalconduction device, as a diode 60, poled in the same direction as diode42. The cathode side of diode 60 is connected to another unidirectionalconduction device, as diode 62, oppositely poled to diode 60 and havingan anode directly connected to the receptacle structure which engagesterminal 19 when the assembly of FIG. 1 is depressed.

Diodes 60 and 62 are shunted by a pair of normally open, single-pole,single-throw switches and 66, respectively. When only switch 64 isclosed, diode 60 is shorted and has no eifect in the circuit. When onlyswitch 66 is closed, diode 62 is shorted and has no effect in thecircuit. When both switches 64 and 66 are closed, both diodes 60 and 62are shunted and effectively disconnected from the circuit.

In operation, when lamp 10 is to be energized, switch 66 is closed,thereby shorting diode 62. Each time the voltage at the upper side ofwinding 56 goes positive, shown by the solid line 80 in FIG. 4, currentflows through diode 60, switch 66, terminal 19 (when the socket isdepressed) and diode 42 to lamp 10, and thence through line 40 andterminal to the lower side of Winding 56.

When only lamp 11 is to 'be energized, switch 64 is closed, shortingdiode 60. Each time the upper side of winding 56 goes negative, shown bythe dashed lines 82 in FIG. 4, current flows through terminal 20 (whenthe socket is depressed) and line 40 to lamp 11, and thence throughdiode 45, line 43, terminal 19, diode 62 and switch 64 to the upper sideof winding 56.

When both lamps are to be energized, both switches 64 and 66 areallowing both half cycles 80 and 82 of alternating current to pass toterminals 19, 20 and energize lamps 10- and 11. That is, during thepositive half cycle 80, FIG. 4, lamp 10 is energized, and during thenegative half cycle 82, lamp 11 is energized. Since conventional AC linecurrent has a frequency of 60' cycles per second, each lamp is energized60 times per second with a 50% duty cycle. "Because this repetition rateis above the perception rate of the human eye, lamps 10 and 11 willappear to be continuously energized.

I claim:

1. In an indicator system having a male assembly movable into contactwith a female receptacle to allow selective energization of a pair ofvisual indicators contained within the male assembly, the improvementscomprising:

a housing forming said male assembly and having an external surface withonly two conductive areas thereon which define two terminals forcontacting said female receptacle to conduct electrical energy from saidfemale receptacle to said male assembly, said pair of visual indicatorsbeing contained within said housing;

first circuit means within said housing and connecting said twoterminals to said pair of indicators for energizing one of saidindicators when electrical energy of one characteristic is presentacross said two terminals and for energizing the other of saidindicators when electrical energy of a different characteristic ispresent across said two terminals; and

source means for connecting electrical energy through said remalereceptacle to said two terminals, including second circuit meansactuable when one of said indicators is to be energized for supplyingelectrical energy of said one characteristic and actuable when the otherof said indicators is to be energized for supplying electrical energy ofsaid different characteristic.

2. The indicator system of claim 1 wherein said first circuit meansincludes a pair of unidirectional conduction devices and meansconnecting each of said devices to a different one of said indicatorsfor energizing the indicator only when a voltage of a polaritycorresponding to the direction of conduction of the device is presentacross said two terminals, wherein said characteristic corresponds tothe polarity of voltage from said source means. I

3. The indicator system of claim 2 wherein said second circuit meansincludes means actuable when both of said indicators are to be energizedfor supplying voltage of alternating polarity through said femalereceptacle to said two terminals, said first circuit means alternatelycausing each of said unidirectional conduction devices to pass currentand alternately energize the indicator associated therewith.

4. The indicator system of claim 3- wherein said AC voltage has afrequency at least two times greater than the perception rate of thehuman eye, said first circuit means alternately energizing each visualindicator at a repetition rate greater than the perception rate of thehuman eye, whereby said pair of visual indicators appear to the humaneye to be continuously energized.

5. The indicator system of claim 3 wherein said second circuit meansincludes a third unidirectional conduction device connected to said ACvoltage supplying means for rectifying the AC voltage to produce halfcycle voltage of positive polarity, a fourth unidirectional conductiondevice connected to said AC voltage supplying means for the AC voltageto produce half cycle voltage of negative polarity, and switch meansactuable to shunt both said third and fourth unidirectional conductiondevices to couple AC voltage of positive and negative polarity throughsaid female receptacle to said two terminals.

6. The indicator system of claim 1 wherein said housing includes lensmeans transparent to light energy emitted by said pair of visualindicators when energized, opaque means in said housing for forming apair of separate light chambers, each chamber being adjacent said lensmeans, and means mounting each of said visual indicators in a differentone of said pair of chambers.

References Cited UNITED STATES PATENTS 3,019,369 1/1962 Zarleng 3152093,110,810 11/1963 Fransen 250-- 3,268,742 8/1966 Pinckaers 30788.5

JOHN HUCKERT, Primary Examiner R. F. POLISSACK, Assistant Examiner U.S.Cl. X.R.

